I think Chris Carmichael wrote the seminal commentary on this. Essentially, you can always find a reason not to go on a ride or a run – too hot, too cold, too dark, raining, too tired etc. Its only through the choice of enduring these things is toughness built.
For me, with chronic obstructive asthma, every interval workout feels like a trial where I’m going to die. I can find a hundred reasons not to go do it. I try to remember Chris’ article every time I start finding myself making excuses and putting something off.
On the other end of the spectrum, I always try to remember General David Morrison’s words while addressing the Australian Army sexual harassment scandal. He very articulately and forcefully reminded all serving Australians that “Toughness is not built through the humiliation of others”.